Check default app (#1918)

* Check .js default app

* Cleanup fallback check

* Check all keys

* Check for empty strings

app/config/open.js

@@ -4,7 +4,56 @@ const {cfgPath} = require('./paths');
 module.exports = () => Promise.resolve(shell.openItem(cfgPath));
 
 if (process.platform === 'win32') {
-  const exec = require('child_process').exec;
+  const Registry = require('winreg');
+  const {exec} = require('child_process');
+
+  // Windows opens .js files with  WScript.exe by default
+  // If the user hasn't set up an editor for .js files, we fallback to notepad.
+  const getFileExtKeys = () => new Promise((resolve, reject) => {
+    Registry({
+      hive: Registry.HKCU,
+      key: '\\Software\\Microsoft\\Windows\\CurrentVersion\\Explorer\\FileExts\\.js'
+    })
+    .keys((error, keys) => {
+      if (error) {
+        reject(error);
+      } else {
+        resolve(keys || []);
+      }
+    });
+  });
+
+  const hasDefaultSet = async () => {
+    const keys = await getFileExtKeys();
+
+    const valueGroups = await Promise.all(keys.map(key => new Promise((resolve, reject) => {
+      key.values((error, items) => {
+        if (error) {
+          reject(error);
+        }
+        resolve(items.map(item => item.value || '') || []);
+      });
+    })));
+
+    const values = valueGroups
+      .reduce((allValues, groupValues) => ([...allValues, ...groupValues]), [])
+      .filter(value => value && typeof value === 'string');
+
+    // No default app set
+    if (values.length === 0) {
+      return false;
+    }
+
+    // WScript is in default apps list
+    if (values.some(value => value.includes('WScript.exe'))) {
+      const userDefaults = values.filter(value => value.endsWith('.exe') && !value.includes('WScript.exe'));
+
+      // WScript.exe is overidden
+      return (userDefaults.length > 0);
+    }
+
+    return true;
+  };
 
   // This mimics shell.openItem, true if it worked, false if not.
   const openNotepad = file => new Promise(resolve => {
@@ -13,21 +62,16 @@ if (process.platform === 'win32') {
     });
   });
 
-  // Windows opens .js files with  WScript.exe by default
-  // If the user hasn't set up an editor for .js files, we fallback to notepad.
-  const canOpenNative = () => new Promise((resolve, reject) => {
-    exec('ftype JSFile', (error, stdout) => {
-      if (error) {
-        reject(error);
-      } else if (stdout && stdout.includes('WScript.exe')) {
-        reject(new Error('WScript is the default editor for .js files'));
-      } else {
-        resolve(true);
+  module.exports = () => hasDefaultSet()
+    .then(yes => {
+      if (yes) {
+        return shell.openItem(cfgPath);
       }
+      console.warn('No default app set for .js files, using notepad.exe fallback');
+      return openNotepad(cfgPath);
+    })
+    .catch(err => {
+      console.error('Open config with default app error:', err);
+      return openNotepad(cfgPath);
     });
-  });
-
-  module.exports = () => canOpenNative()
-    .then(() => shell.openItem(cfgPath))
-    .catch(() => openNotepad(cfgPath));
 }